1. Field of the Invention
This invention relates to a cooperative work support system which displays a common screen on computer screens of a plurality of users to support cooperative work among the users through the screen display.
2. Description of the Prior Art
There is conventionally known a system in which shared data is displayed as a shared window on the display screens of computers of participants in a meeting via a computer network to exchange messages in real time among the meeting participants.
Well-known examples of a system of this type are Colab System (refer to M. Strefix, D. G. Bobrow, G. Foster, S. Lanning, and D. Tatar Xerox Palo Alto, Research Center "WYSIWIS Revised: Early Experiences with Multiuser Interfaces", ACM Transaction on Office Information Systems, Vol. 5, No. 2, April 1987, Pages 147-167) and MERMAID (refer to Japanese Published Unexamined Patent Application No. Hei 3-58658) by Nippon Electric Co., Ltd.
In a system of this type, for example, when a plurality of persons at remote locations are to hold consultations, a group for the consultations is formed by specifying the addresses of computers including workstations of the persons, and application programs required for the consultations, written on the assumption that they are used by a plurality of persons are started by a computer of their own. Data is exchanged among the application programs, application screens displayed on their computers are made exactly identical, and the results of operations performed within the shared window and changing displays are also made identical. As a result, individual operators can perform operations in each of the plurality of computers while sharing one application (e.g., white board tool) to conduct discussions.
This specification refers to as a screen sharing system the system in which communications are performed among a plurality of persons via a network by sharing screen displays and operations by a plurality of persons through input operation units such as a mouse and a keyboard in units of applications created on the assumption that they are used by a plurality of persons.
On the other hand, instead of displaying screens and performing input operations by means of a mouse, a keyboard, etc. in units of applications as described above, there is also known a system in which communications are performed among a plurality of persons by sharing screen displays of a window system in which a plurality of applications are displayed, and operations by a mouse, a keyboard, etc. performed through the window system.
Well-known examples of a system of this type are TeamWorkstation of Nippon Telegraph and Telephone Corp. (refer to Ishii, Hiroshi. "TeamWorkstation: Towards a Seamless Shared Workspace" CSCW 90 Proceedings, October 1990, pp. 13-26 and Japanese Published Unexamined Patent Application No. Hei 3-119476), Timbuktsu, Look@Me (Look@Me Release Notes, Farallon Computing, Inc.), and a cooperative work system (e.g., refer to Japanese Published Unexamined Patent Application No. Hei 3-273443). This specification refers to a system of this configuration as an application sharing system.
The screen sharing system and the application sharing system described previously will be further described using the accompanying figures.
FIG. 15 describes a screen sharing system. That is, in this system, required application programs M written on the assumption that they are used by a plurality of persons are installed in computers A and B, and the application programs M are connected by a communication network N. User input units Ca and Cb such as a mouse, a keyboard, etc. and display units Va and Vb are connected to the computers A and B, respectively.
In this screen sharing system, input events from the user input unit Ca of the computer A are processed by the application M of the computer A and the processing results are displayed on the display unit Va, while the events are transferred to the application M of the computer B through the communication network N and processed, and the processing results are displayed on the display unit Vb of the computer B.
As a result, a window having identical processing contents of the application M is displayed on the display screens of the computers A and B. That is, each of input events from the user input units Ca and Cb is reflected common to the computers A and B. Accordingly, the owners of the computers A and B can perform cooperative work through the shared window while using the user input units Ca and Cb.
Next, FIG. 16 describes an application sharing system. Namely, in this system, a plurality of applications M including an application for managing windows shared by a plurality of computers are installed in a computer of one user. The applications M are not special ones written on the assumption that they are used by a plurality of persons, but usually can be general purpose applications used in individual computers.
In the application sharing system, with no modifications made to the general purpose applications, a shared device (shared module) is installed in each computer and the shared devices are connected by a communication network N.
In this system, although the applications M support only one user input unit because they are general purpose applications, the shared device performs control as if the operation inputs of user input units Ca and Cb of a plurality of computers A and B were the operations of a single user input unit for the applications M. The applications M of the computer A process input events by all user input units Ca and Cb and display the processing results not only on the display unit Va of the computer A but also on the display unit Vb of the computer B.
In this way, the application sharing system shares a plurality of applications M between a plurality of computers A and B, and window screens are identically displayed on the display screens Va and Vb by the applications M.
However, as described previously, the above-mentioned screen sharing system requires special applications written on the assumption that they are used by a plurality of users. Namely, there has been a problem that applications other than special ones written for shared use by a plurality of users cannot be shared by a plurality of persons.
Also, since a screen is shared in units of applications, when a mouse cursor goes out of the screen, the mouse cursor cannot be shared. For this reason, there has been a problem that, when discussions are made using a plurality of applications by a plurality of persons, it is difficult to make discussions and explanations based on information extending onto a plurality of windows of a plurality of applications. Further, even in an identical application, when different pieces of information are opened, they may be displayed as different windows, in which case the information extends onto a plurality of application windows.
On the other hand, according to an application sharing system, since general purpose applications can be used and applications (including an application for managing windows) of one computer manage user input units and display screen information of a plurality of computers, management of mouse cursors is facilitated and discussions can be made using a relationship among information items extending onto a plurality of application windows.
However, this application sharing system has a problem that information of all the opened windows is revealed to others and information that should be kept secret from others cannot be privately opened. The above-mentioned screen sharing system is also similar to the application sharing system in that all the meeting participants view the same screen and different participants cannot view a different screen. However, there are situations in which information should be revealed to specific persons but not to others during a meeting or consultation.